The invention relates to a drilling and/or chiseling device with a drive spindle for a tool with a countershaft parallel to the drive spindle, a drive pinion rotationally connected to the countershaft and interacts in rotational engagement with a power take-off pinion of a drive motor. A wobble drive for a striking mechanism mounted on the countershaft with a switching sleeve positioned on the countershaft for axial displacement by a switching element.
For working on concrete, stone, masonry, or the like, a drilling and/or chiseling device with a drive spindle for a drilling and/or chiseling tool, driven by a drive motor, as well as a striking mechanism, which is connected with the drive spindle, strikes the drilling and/or chiseling tool with axial strokes, by means of the drive spindle, is known from German patent 33 22 963. Parallel to the drive spindle, there is a further spindle, which can be connected with the drive motor and has a drill chuck, which serves to hold a drilling tool, which can only be used for drilling work without impact strokes. This additional spindle can be driven at a higher rotational speed than can the drive spindle.
A ring gear is connected with the drive spindle and with the further spindle, in each instance, so that there is no mutual rotation. The ring gear, which is disposed on the drive spindle, has a diameter greater than that of the ring gear, which is disposed on the additional spindle. These two ring gears can be connected rotationally engaged over a gear mechanism with a power take-off pinion of the drive motor.
The gear mechanism of the drilling and/or chiseling device has a countershaft arranged parallel to the two spindles, with a drive pinion that interacts rotationally connected with the power take-off pinion of the drive motor. On the countershaft, there is a wobble drive for a striking mechanism, mounted rotationally engaged. A switching sleeve, which can be axially shifted using a switching element is also connected rotationally engaged with the countershaft. This switching sleeve has an orbiting collar with an orbiting groove, into which a selector fork of the switching element extends. Two different modes of operation of the drilling and/or chiseling device can be set using the switching sleeve. In a first mode of operation, a first gear ring interacts rotationally connected with a counter ring gear of the wobble drive and the ring gear of the drive spindle. In a second mode of operation, the switching sleeve interacts rotationally engaged only with the ring gear of a further spindle.
The limited usability of this drilling and/or chiseling device is considered to be a very great disadvantage, since only two different modes of operation can be set. In a first mode of operation, the drive spindle has a low rpm and the activated wobble drive has a high wobbling frequency. In a second mode of operation, the drive spindle has a high rpm and the wobble drive is not activated. In particular, a good drill hole quality and good holding values for fastening elements, for example, in the form of dowels, in a receiving material made up of hollow bricks, for example, which have a large number of hollow chambers, cannot be achieved with this drilling and/or chiseling device. The progress of drilling when drilling without impactxe2x80x94the second mode of operationxe2x80x94is very slow, and because of the high rpm of the further spindle, as well as because of the high friction between the drill tip and the receiving material, the drill tip of the drilling tool wears out. In addition, the impact strength cannot be varied with this drilling and/or chiseling tool, accordingly, when working on the aforementioned masonry composed of fired bricks, it can be expected that the walls that define the hollow chambers will be shattered, so that they can no longer serve to fix the fastening elements.
It is an object of the invention to provide a drilling and/or chiseling device, which can be operated easily and safely and can be used in many different ways, and with which very good progress of drilling can be achieved and for which the impact energy can be varied while the rpm of the drive spindle remains constant.
These objectives are accomplished with a drilling and/or chiseling device that has the distinguishing features of two outer ring gears on the countershaft that it is possible a first outer ring gear is meshed in rotational engagement with a ring gear on the switching sleeve and the outer ring gear is meshed with a further ring gear connection for rotation with the drive spindle
For the inventive drilling device, four different modes of operation can be set:
first mode of operation: low rpm of the drive spindle; wobble drive activated, with a high wobbling frequency;
second mode of operation: low rpm of the drive spindle; wobble drive not activated;
third mode of operation: low rpm of the drive spindle; wobble drive activated, with a low wobble frequency; and
fourth mode of operation: high rpm of the drive spindle; wobble drive not activated.
These modes of operation can be set using the switching sleeve, which can be moved axially relative to the countershaft and shifted into four different positions along the countershaft using the switching lever. The rotational movement of the countershaft is transferred over the two outer ring gears, on the one hand, directly to the switching sleeve and, on the other, directly to the further ring gear of the drive shaft. Since the second outer ring gear is always rotationally engaged with the further ring gear of the drive spindle in the first, second, and third modes of operation, the drive spindle is rotated at a uniform rpm in these three different modes of operation. A first ring gear of the switching sleeve, which is constructed as an inner ring gear also remains rotationally engaged in all three modes of operation with the counter-ring gear of the wobble drive, which is structured as an outer gear arrangement. In order for this to be possible, the axial length of the counter-ring gear corresponds to the axial length of the first ring gear and to the total path, by which the switching sleeve can be shifted in one direction.
With the help of the switching sleeve, a rotational connection between the countershaft and the wobble drive is brought about in the first mode of operation. In this connection, a second ring gear of the switching sleeve, which is constructed as an inner ring gear, interacts in a rotationally engaged manner with the first outer ring gear of the countershaft. Since the switching sleeve is rotationally connected directly with the first outer ring gear, the speeds of rotation of the countershaft and the wobble drive are the same. The wobble drive has a high wobbling frequency.
To set the second mode of operation for the inventive drilling and/or chiseling device, the switching sleeve is shifted along the countershaft by one position, in the working or drilling direction. In this connection, the rotational connection between the second ring gear of the switching sleeve and the first outer ring gear of the countershaft is severed, so that the rotational movement of the countershaft is no longer transferred to the switching sleeve and from the latter to the wobble drive.
In order to be able to achieve a lesser wobbling frequency and, therefore, a lower impact energy in the third mode of operation than in the first mode of operation, it is necessary to reduce the rpm of the wobble drive. This is achieved with the help of the switching sleeve, which interacts in rotational engagement with the ring gear of the drive spindle in the third mode of operation. The further ring gear of the drive spindle is connected for rotation with the second outer ring gear on the countershaft. In order to be able to achieve a lower rpm of the switching sleeve, the further ring gear, which interacts with the countershaft, advisably has a diameter larger than that of the ring gear, which can be connected rotationally with the switching sleeve. In the third mode of operation, the second ring gear, which is disposed in the interior of the switching sleeve, is not connected rotationally engaged with the countershaft.
For manufacturing reasons, the switching sleeve advantageously has a third ring gear that can be brought into a rotational connection with the smaller ring gear.
In order to be able to keep the switching path of the switching sleeve as short as possible, the ring gear advantageously is disposed between the first ring gear and the switching sleeve.
In order to create a rotational connection between the first ring gear of the switching sleeve and the first outer ring gear of the countershaft, the outer ring gear advisably is constructed as large as the counter-ring gear of the wobble drive.
To keep the overall length of the drilling and/or chiseling device as short as possible, the two ring gears are constructed as a modular unit, in which the two ring gear are disposed coaxially and at a short distance from one another.
For the purpose of achieving a high rpm at the drive spindle in the fourth mode of operation without activating the wobble drive, the countershaft, the switching sleeve and the driving spindle interact rotationally engaged. To be able to disengage the large ring gear of the modular unit from the second outer ring gear of the countershaft, the modular unit advantageously can advisably be shifted with the help of the switching element along the driving spindle in the working direction counter to the force of a spring.
Precise shifting of the switching sleeve along the countershaft and of the two ring gears along the driving spindle is ensured in that preferably the switching element has a selector fork and a stop facing in the working direction. The selector fork engages a groove of a collar on the switching sleeve. The stop can be connected with a face of the second ring gear facing counter to the working direction. The switching element is connected, for example, with a control knob that can be actuated outside of the drilling and/or chiseling device and with the help of which the four different modes of operation can be set. For example, a cam is disposed between the control knob and the switching element and converts the rotational movement of the button into a longitudinal movement acting on the switching element.
The invention is explained in greater detail below by means of drawings showing an embodiment of the invention.